Extended operation for T4 lung carcinoma

PURPOSE: The study objective was to determine an "optimal" individual pressure support (PS) level for beginning weaning with PS ventilation in patients with chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: Eleven COPD patients intubated and ventilated for acute respiratory failure and judged ready for weaning were studied. The technique consisted of lowering the PS level from a point that was characteristic for each patient and measurable under controlled mechanical ventilation, after setting the ventilator as recommended for COPD patients judged ready for weaning, that is, peak inflation pressure (PIP). This determination was based mainly on exploring the diaphragm with an electromyographic technique by defining the optimal PS level as the lowest PS level associated with no EMG evidence of diaphragmatic stress. Diaphragmatic electromyographic activity (diEMG) was recorded by a bipolar esophageal electrode (Disa-Denmark), and the high-frequency electrical component/low-frequency ratio (H/L) was calculated. The reference H/L was determined during a few spontaneous ventilatory cycles. Muscle stress was defined as a greater than 20% reduction in H/L compared with the reference value. RESULTS: Optimal PS levels ranged from 4 to 24 cm H2O with a mean of 14+/-6 cm H2O. Two patients with optimal PS level at 4 cm H2O did not require weaning and were quickly extubated. For the nine other patients, optimal PS levels were found to be 70% of PIP; in none was it necessary during weaning to use PS levels higher than individual optimal PS levels. CONCLUSIONS: Optimal PS level established with diEMG monitoring seems to be a useful index for beginning weaning in the PS ventilation mode in COPD patients. The hypothesis of beginning weaning with a PS level equal to 70% of PIP needs to be tested.     

An intelligent control system for ventilators

This study reports on a ventilator system that consists of several intelligent modules for controlling ventilator operation. These modules are software programs in two controllers. One controller is a personal computer used for diagnoses, determining settings and checking the effects of settings. The other controller is a single-chip microprocessor in a ventilator that controls the ventilator's settings in accordance with the computer settings. After setting up the system, an artificial lung model simulating a patient's lung is used to test the system. The result of test run indicated that it always responds to a patient's lung condition in a stable manner. Thus, the proposed system with its intelligent modules may assist clinicians in caring for patients and managing ventilator operation.     

Weaning from mechanical ventilation

For the ventilator-dependent patient, weaning should be accomplished by withdrawing support safely, efficaciously, and efficiently. Success depends largely on physiologic determinants of respiratory system function, avoidance of ventilator-associated complications, and attention to patient readiness. Recent clinical trials, predictors of weaning, current techniques of weaning, the concept of reloading the respiratory pump, and determinants of ventilator dependency are all discussed.     

The future of genetic studies of complex human diseases: an epidemiologic perspective

Every intubated and mechanically-ventilated patient should be clinically evaluated, at least on a daily basis, by a skilled team in order to speed up the weaning process as much as possible. Again, it should be emphasized that the adoption of an active clinical strategy when faced with "difficult" to wean patients is of paramount importance. In one study, performed in Spain, analysing the prevalence of mechanical ventilation in intensive care units [3], reported the mean number of days that patients spent on mechanical ventilation was 27. In a more recent intervention study, in which a specific protocol was followed each day [2], the mean number of days on mechanical ventilation was only 12. These data have been confirmed by several authors [4, 40], and it has also been reported that a protocol-directed weaning strategy leads not only to a significant reduction in the duration of mechanical ventilation but also to a significant decrease in the number of complications and cost [4]. However, even following a protocol-directed weaning strategy, it is possible that weaning duration can be further reduced. In a prospective study performed in our institution [41] during 32 months, we reported that, following an episode of unplanned extubation, the only independent variables associated with the need for reintubation were the number of days of mechanical ventilation and the type of ventilatory support at the time of autoextubation. Indeed, when patients were in the weaning period only 16% (5 out of 32) needed reintubation, whereas reintubation was needed in 82% (22 out of 27) of patients who had an unplanned extubation during full mechanical ventilatory support. These data suggest that there are still some patients being on mechanical ventilation for a longer than necessary period of time. Finally, very recent advances in technological areas such as artificial intelligence, are proving to be useful in the management of the weaning process. When such systems are applied to modern microprocessor-controlled mechanical ventilators they can significantly help in the process of weaning [42] by automatically reducing the ventilatory assistance and by indicating the optimal time to withdraw the patient from the ventilator and proceed with extubation.     

Options for long-term ventilatory support

Long-term mechanical ventilator support for patients with chronic respiratory failure is becoming more common. This article reviews the common causes for chronic ventilator dependence, and offers an approach to weaning these patients from the ventilator. In addition, the details for preparing these patients for prolonged mechanical ventilation outside of the acute-care hospital setting are discussed. Appropriate education of the patient's caregivers is key to the success of long-term ventilatory support outside of the acute-care hospital.     

Epidemiologic panorama of viral hepatitis in Mexico

The effects of continuous positive airway pressure (CPAP) provided by the Siemens Servo 900C ventilator were compared with a continuous flow system (CF-CPAP) in patients weaning from the ventilator. Thirteen patients were studied using both systems at a CPAP level of 0.5 kPa. Additional work of breathing (Wapp) and derived variables were determined in relation to the minute volumes of the patients. The Wapp imposed by the ventilator exceeded the Wapp of CF-CPAP in all patients. The difference in Wapp between ventilator- and CF-CPAP was greater at higher ventilatory needs. The increments in Wapp imposed by the ventilator were positively correlated with the actual end-expiratory pressures (EEP). The EEP increasingly exceeded the preset CPAP level of the ventilator at higher minute volumes. An inspiratory threshold due to a gradient between EEP and preset CPAP greatly increased the Wapp imposed by the ventilator. As this threshold was attributed to the resistance of the PEEP device of the ventilator, it indicates that the additional work related to the expiratory value should be taken into account when the Siemens Servo 900C ventilator is used for weaning purposes.     

Weaning from mechanical ventilation: concept development

This article, the first in a series, is written to clarify the process of weaning from mechanical ventilation and to promote the development of a common language for understanding the complex weaning process. The Third National Study Group on Weaning From Mechanical Ventilation proposes a conceptual model and definitions that will provide a framework for future research on this important topic. This conceptual framework describes the preweaning phase, the weaning process, and the outcome phase of mechanical ventilation. Potential outcomes are completion of weaning, lack of completion, and terminal weaning. The weaning decision continuum incorporates: (1) when and how to begin the weaning process, (2) how to select therapies to assist with difficult weaning and chart progress during weaning, and (3) when to stop weaning if progress is no longer being made. An inherent assumption of this model is that each patient will display unique responses to the weaning process. The proposed conceptual framework and definitions provide a foundation for developing clinical practice guidelines and for guiding future ventilator weaning research.     

Difficult weaning from mechanical ventilation: a graduated approach and teamwork

Weaning from mechanical ventilation in patients with chronic obstructive pulmonary disease (COPD) or left ventricular failure may be difficult. At the time of intubation and initiation of mechanical ventilatory support, this treatment is usually life-saving in the short term. Only later on, the condition which necessitated such support may prove irreversible. COPD patients often require positive end-expiratory pressure to enable them to trigger the ventilator comfortably. Patients with left ventricular failure need pharmacological support to reduce the circulating volume and to reduce left ventricular afterload because the ventilatory support itself reduces both left ventricular preload and afterload. Gradual withdrawal of pressure support and gradually increasing periods of T-piece weaning are probably equally effective. New methods have been described but have not yet been tested in randomized controlled trials. More important than the method of weaning is the presence of qualified and dedicated nursing support. Not all patients can be weaned; for most of those who cannot, prospects are grim. These patients require optimal palliative support with recognition of their autonomy.     

Neuromuscular disorders associated with failure to wean from the ventilator

OBJECTIVE: To determine, by retrospective chart analysis, the frequency, type and significance of neuromuscular disorders in patients whose clinical features suggested a neuromuscular cause of failure to wean. BACKGROUND: Failure to wean is a common and difficult problem in critical care units. While a neuromuscular cause may be suspected in some patients, the frequency and type has not been determined utilizing comprehensive electrophysiological studies of limbs and the respiratory system. Such knowledge may aid in patient management and prognosis. METHODS: The clinical setting was a critical care/trauma centre that admits 1500 patients per year, approximately 500 being on ventilators for longer than five days. We analyzed the hospital charts of 40 patients admitted to the unit during three years, whose respiratory assessment suggested a neuromuscular cause for failure to wean from the ventilator. To investigate this possibility, we performed electrophysiological studies of the limbs and also of the respiratory system by phrenic nerve conduction and needle electromyography of the chest wall and diaphragm. The results were compared to 25 healthy controls. RESULTS: 38 of 40 patients (95%) had a neuromuscular disorder: 25--critical illness polyneuropathy, 2--Guillain-Barré syndrome, 4--diabetic and critical illness polyneuropathy, 2--uremic and critical illness polyneuropathy, 10--an abnormality of central drive, 5--unilateral phrenic nerve palsy, 3--a neuromuscular transmission defect, and 5--a primary myopathy. Fifteen (38%) had a combination of disorders. Patients with more severe polyneuropathy took longer to wean, a mean of 136 versus 52 days (p = 0.007). The severity of the polyneuropathy had no effect on mortality. CONCLUSIONS: Electrophysiological studies of limbs and the respiratory system are together valuable in confirming the presence, and identifying the specific type of neuromuscular cause for difficulty in weaning from the ventilator. This information is important in patient management and prognosis.     

A regional weaning center for patients requiring mechanical ventilation: an 18-month experience

This report reviews the outcomes of patients on mechanical ventilation admitted to a new regional weaning center. We reviewed the records of 47 patients admitted to the weaning center over an 18-month period. All patients had a tracheostomy, were ventilator dependent, and considered difficult to wean by their referring physician. The mean days of ventilator dependence prior to transfer to our facility was 86 days, with a range of 21 to 332 days. Patients were admitted to a 12-bed weaning unit at our chronic disease and rehabilitation hospital and assessed by a multi-disciplinary team of physicians, nurses, and therapists. Thirty patients were successfully weaned from prolonged mechanical ventilation and subsequently discharged from our unit. These data indicate that the majority of difficult to wean patients admitted to our regional weaning center were successfully liberated from prolonged mechanical ventilation.     

EPR evidence for the involvement of free radicals in the iron-catalysed decomposition of qinghaosu (artemisinin) and some derivatives; antimalarial action of some polycyclic endoperoxides

The role of pharmacies that specialize in the treatment of specific chronic diseases in the alternate-site health care setting is discussed. The optimal use of medications through disease management programs can improve patient outcomes and lower overall health care costs. The increase in disease management programs has spawned the growth of disease-specific pharmacies in the home care and other alternate-site health care settings. These pharmacies usually operate from a single location or are regionalized operations that deliver pharmaceutical products to patients throughout the United States. The pharmacies employ clinicians who specialize in a particular disease. These clinicians conduct comprehensive patient education programs, drug-use review, and compliance monitoring. Disease management pharmacies focus on chronic, expensive diseases; costs related to inventory, equipment, and storage can be very high. Many disease management pharmacies are involved in preferred-distribution or closed-distribution arrangements with pharmaceutical manufacturers. Pharmacists involved in disease management programs routinely send compliance information about their patients to pharmaceutical companies, managed care organizations, or prescribing physicians. Disease management pharmacies act as advocates for patients with particular chronic diseases. Various foundations and patient advocacy and research groups have created their own disease management pharmacies. Disease management has also reached the community pharmacy practice setting. Pharmacies specializing in the treatment of specific chronic diseases in the alternate-site health care setting can improve health care and promote efficient use of health care dollars.     

Successful weaning from mechanical ventilation in an aged subject with severe apneas due to brain damage

A 73-year-old male was admitted to Tokyo University Hospital due to cardiac arrest secondary to ventricular arrhythmias. Although the patient survived after cardiopulmonary resuscitation, he needed mechanical ventilation. When we tried to wean the patient from mechanical ventilation, we found that he suffered from frequent sleep apneas of over 40 times/hour. To evaluate the severity and frequency of the apneas, we performed polysomnographic study on the patient under assist ventilation. The polysomnographic study revealed that frequency of apneas was very high but the magnitude of desaturation was not so severe during the night. Since we confirmed the lowest SaO2 in this patients was over 90% during day and night, we tried to wean from the patient from the ventilator again and succeeded. The clinical application and usefulness of nocturnal ventilatory monitoring for patients with mechanical ventilation was discussed.     

Respiratory response to salbutamol (albuterol) in ventilator-dependent infants with chronic lung disease: pressurized aerosol delivery versus intravenous injection

OBJECTIVE: To compare the effects of intravenously injected with inhaled salbutamol in ventilator dependent infants with chronic lung disease (CLD). DESIGN: Prospective randomized study which each patient served as his/her own control. SETTING: Multidisciplinary neonatal and pediatric ICU. PATIENTS: 8 ventilator dependent premature infants with CLD. INTERVENTIONS: Salbutamol, 10 micrograms/kg was given intravenously, and 10-19 h later, twice 100 micrograms as pressurized aerosol, or vice versa, sequence randomized. The pressurized aerosol was delivered by a metered dose inhaler into a newly developed aerosol holding chamber, integrated into the inspiratory limb of the patient circuit. Respiratory system mechanics were assessed by the single breath occlusion method before and 10 and 60 min after drug administration. MEASUREMENTS AND RESULTS: Compliance improved significantly after intravenous injection (0.48 +/- 0.18 to 0.67 +/- 0.16, p < 0.01 and 0.59 +/- 0.23 ml/cmH2O/kg, NS, (mean +/- 1 SD) and after inhalation (0.46 +/- 0.19 to 0.64 +/- 0.32, p < 0.01 and 0.56 +/- 0.31 ml/cmH2O/kg, NS). Resistance decreased after iv. use (0.38 +/- 0.17 to 0.25 +/- 0.11, p < 0.001 and 0.25 +/- 0.10 cmH2O/ml/s, NS) and after inhalation (0.35 +/- 0.12 to 0.27 +/- 0.09, p < 0.01 and 0.28 +/- 0.12 cmH2O/ml/s, NS). Heart rate increased significantly after both routes of application, whereas mean arterial pressure, respirator settings, FIO2, transcutaneous SO2 and capillary PCO2 did not change. CONCLUSIONS: Inhaled and intravenous salbutamol improves pulmonary mechanics to the same extent with comparable side effects, and may therefore be used to facilitate weaning from respirators.     

Surgery for epidermolysis bullosa in children: value of the association of inhalation anesthesia and locoregional anesthesia

Due to the cutaneous and mucosal fragility associated with epidermolysis bullosa, this disease is a source of various practical problems for the anaesthesiologist concerning the surgical posture, the monitoring of vital functions, the airways control and the vascular access, as all these procedures may worsen, sometimes dramatically, the lesions in these young patients, still in a precarious health state. Basing on published studies and their own experience, the authors have used in these patients a combined locoregional and general anaesthesia. The latter was obtained with isoflurane, administered in the non intubated and spontaneously breathing patient through a closed surgical isolation container (Vi-Drape), including the patient's head and ventilated with a ventilator generating a PEEP for long procedures. The results obtained during 9 procedures in 3 children are reported and discussed. For several shorter procedures (for example wound dressing), intramuscular ketamine was used.     

Nitric oxide delivery through ventilator and its toxic oxidative product nitrogen dioxide

OBJECTIVE: To observe nitric oxide(NO) delivery through mechanically ventilator. NO is rapidly converted to nitrogen dioxide(NO2)in oxygen(O2) environments. METHODS: NO(800 ppm)was blended with compressed air, delivered to the high-pressure air inlet of a Siemens Servo 900C or VIP BIRD ventilator, and used to ventilator as a test lung. The ventilator settings were varied, minute ventilation (VE)from 2 to 6 L/min, inspired O2 fraction(FiO2)from 0.25 to 0.65, and NO concentration from 10 to 80 ppm. The inspiratory gas mixture was sampled just at the outlet port of ventilator. NO and NO2 were measured both by hemiluminescence and electro-chemical fuel cell technique. RESULTS: No NO was detected during any trial with VE 5 or 6 L/min., with FiO2 0.35 or 0.25, with NO 20 or 10 ppm. Low VE and low NO, NO2 values were greater with Servo 900C ventilator than with VIP BIRD ventilator at similar settings High VE and low NO or low VE and high NO, NO2 values were similar with both ventilators. High VE and high NO, NO2 values were greater with VIP BIRD ventilator than with Servo 900C ventilator. At same VE, NO2 values increased with increased FiO2 and NO. (NO2) = 0.0607 (NO)- 0.6604 VE + 7.004 FiO2, R2 = 0.7649 with Servo 900C ventilator,(NO2) = 0.0929(NO)- 0.1296 VE + 7.9360 FiO2, R2 = 0.8687 with VIP BIRD ventilator. CONCLUSIONS: NO(800 ppm) was blended with compressed air, delivered to the high-pressure air inlet of a Siemens Servo 900C or VIP BIRD ventilator is a portable, accurate, and adaptable system to deliver NO. During NO inhalation, VIP BIRD ventilator is more adaptable while low VE. Servo 900C ventilator is more adaptable while high VE.     

Liberation from mechanical ventilation: a decade of progress

Multiple complications associated with mechanical ventilation mandate that clinicians expeditiously define and reverse the pathophysiologic processes that precipitate respiratory failure and then, detect the earliest point that a patient can breathe without the ventilator. Over the past decade, numerous laboratory and clinical studies have been reported that may inform transformation of the "art of weaning" to the science of liberation. We review these studies and use them to formulate a systematic approach to assure early, safe, and successful liberation of patients from mechanical ventilation.     

Outreach education to improve quality of rural ICU care. Results of a randomized trial

This study tests whether an outreach educational program tailored to institutional specific patient care practices would improve the quality of care delivered to mechanically ventilated intensive care unit (ICU) patients in rural hospitals. The study was conducted as a randomized control trial using 20 rural Iowa hospitals as the unit of analysis. Twelve randomly selected hospitals received an outreach educational program. After review of the medical records of eligible patients, a multidisciplinary team of intensive care unit specialists from an academic medical center delivered an educational program with content specific to the findings and capacity of the hospital. The outcome measures included patient care processes, patient morbidity and mortality outcomes, and resource use. Results indicated that the outreach program significantly improved many patient care processes (lab work, nursing, dietary management, ventilator management, ventilator weaning). The program marginally reduced hospital ventilator days. Both total length of stay and ICU length of stay fell markedly in the intervention group (by an average of 3.2 and 2.1 d, respectively), while the control group fell only 0.6 and 0.3 d, respectively. However, these effects did not reach statistical significance. Unfortunately, the program had no detectable effects on the clinical outcomes of mortality or nosocomial events. We conclude that an outreach program of this type can effectively improve processes of care in rural ICUs. However, improving processes of care may not always translate into improvement of specific outcomes.     

Decrease in ventilation time with a standardized weaning process

OBJECTIVE: To test the hypothesis that standardizing the process of weaning from mechanical ventilation would decrease ventilation times and length of stay in a surgical intensive care unit. DESIGN: Comparison of historic ventilation times with physician-directed weaning with those obtained with protocol-guided weaning by respiratory therapists. SETTING: Urban, teaching surgical intensive care unit with open admission policy and no dominant diagnosis related group. RESULTS: From January 1, 1995, through December 31, 1995, 378 patients who underwent physician-directed weaning from a ventilator had 64488 hours of ventilation, compared with 57796 ventilation hours in 515 patients with protocol-guided weaning (April 1, 1996, through May 31, 1997). The mean hours of ventilation decreased by 58 hours, a 46% decrease (P<.001). The length of hospital stay decreased by 1.77 days (29% change), while the Acute Physiology and Chronic Health Evaluation III score remained at 50 to 51. The number of reintubations did not change. The marginal cost savings was $603580. CONCLUSION: Protocol-guided weaning from mechanical ventilation leads to more rapid extubation than physician-directed weaning and has great potential for cost savings.